It is known that molybdenum is an active catalyst for important epoxidation reactions conducted upon olefins containing 3 to 18 carbon atoms. As an example, propylene oxide produced by the hydroperoxide epoxidation of propylene is an important industrial intermediate which is produced in large quantities. Molybdenum catalysts for use in such reactions may be produced as described in U.S. Pat. No. 3,453,218 by dissolving molybdenum metal powder in an organic acid such as formic acid containing a small amount of a hydroperoxide such as t-butyl hydroperoxide. Spent catalyst is removed from the process as a solution of molybdenum in a complex brew of organic compounds including process reactants, products and byproducts. The molybdenum content of the organic can vary considerably, between 0.5% molybdenum, or even less, and can be increased, as by distillation of the spent catalyst mixture to 40%, or even more. The consistency of the spent catalyst can vary between that of a mobile liquid to that of a thick, viscous tar. The organic has value as fuel as it can yield 12000-13000 BTU/lb. The value of the spent catalyst would be increased considerably if the molybdenum content could be recovered as metal or in a form suitable for producing a fresh, active catalyst. Hydrometallurgical processes for this purpose have been proposed and are discussed in numerous U.S. Pat. including Nos. 3,453,068, 3,598,519, 3,763,303, 3,931,041, 4,046,852, 4,315,896, 4,317,801, and 4,328,191. The present invention affords a fresh approach to solution of the problem as compared to the teachings of the aforementioned patents.